In a letter sent to the White House on Thursday, McKeon wants American field commanders "to conduct a reassessment" of the Counter Rocket, Artillery and Mortar (C-RAM) intercept system in Afghanistan.
But the weapon, designed to take out incoming artillery and mortar rounds fired at American and coalition bases in country, was pulled from Afghanistan due to the administration's troop withdrawal plan.
This summer, roughly 32,000 U.S. troops attached to the White House's 2009 surge strategy in Afghanistan were withdrawn from the country.
The remaining 68,000 will cycle back to the United States over the next two years, as part of the administration's plan to completely pull out from Afghanistan by 2014.
But due to that limited U.S. force, American military leaders were unable to deploy the C-RAM to the American units still operating in the country.
"The Army agreed that the systems were available for deployment and determined that approximately 80 to 100 additional forces per site would have to be deployed to support the C-RAM" in Afghanistan, McKeon wrote.
With one-third of those forces now gone, there are not enough troops on the ground to justify the C-RAM deployments, according to McKeon.
To get the weapon into Afghanistan, U.S. commanders would have to pull troops "already committed to other missions" and send them back in country to meet the Army's threshold, according to McKeon.
"Consequently [U.S. commanders] decided to accept greater risk for forces in Afghanistan" in order to comply with the administration's 2014 deadline, the House committee chief wrote.
With American casualties in Afghanistan on the rise due to mortar and artillery attack, "I implore you to rescind the force cap restriction so that our commanders are not forced into the dilemma of choosing between executing their mission and protecting lives," McKeon said.
"If a C-RAM intercept capability would protect our troops against lethal threats without detraction from our mission in Afghanistan, please immediately order the deployment of these weapon systems," he added.